<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        ul {
            display: block;
            width: 800px;
            height: 30px;
            margin: 100px auto 0;
            border: 1px solid #CCCCCC;
            position: relative;
            overflow: hidden;
        }
        li {
            list-style: none;
            float: left;
            width: 99px;
            height: 30px;
            text-align: center;
            line-height: 30px;
            border-right: 1px solid #CCCCCC;
        }
        li:nth-child(8) {
            border-right: 0;
        }
        span {
            display: block;
            width: 100px;
            height: 30px;
            background: skyblue;
            position: absolute;
            top: 0;
            z-index: -1;
        }
    </style>
    <script src="jquery-3.2.1.min.js"></script>
    <script>
        $(function () {
            var colorArr = ['yellow','red','purple','blue','pink','orange','deeppink','darkkhaki'];
            $('span').each(function (i) {
                $(this).css({'background':colorArr[i],'top':30});
            })
            $('li').mouseover(function () {
                $(this).children('span').stop().animate({'top': 30})
            }).mouseout(function () {
                $(this).children('span').stop().animate({'top': 0})
            })
        })
    </script>
</head>
<body>
<ul>
    <li>
        <em>1</em>
        <span></span>
    </li>
    <li>
        <em>2</em>
        <span></span>
    </li>
    <li>
        <em>3</em>
        <span></span>
    </li>
    <li>
        <em>4</em>
        <span></span>
    </li>
    <li>
        <em>5</em>
        <span></span>
    </li>
    <li>
        <em>6</em>
        <span></span>
    </li>
    <li>
        <em>7</em>
        <span></span>
    </li>
    <li>
        <em>8</em>
        <span></span>
    </li>
</ul>
</body>
</html>